A semiconductor device including vertical field effect transistors may comprise a buried insulating film stacked on a semiconductor substrate and spaced apart first and second active regions vertically penetrating the buried insulating film. The optical absorption and emission wavelengths of a quantum dot are governed by the particle size. A laser beam source generates a continuous laser beam and a deflection mirror directs the laser beam onto the material web. 6 degrees while the second blocking surfaces have a zero degree pressure angle and are slightly spaced from each other.